1. Field of the Invention
The present invention relates to an AC plasma display panel used for an information displaying terminal, flat-panel television, or a like and more particularly to a structure of the AC plasma display panel.
2. Description of the Related Art
Currently various types of AC plasma display panels are available for use. A three-electrode-surface-discharge type of AC (Alternating Current) plasma display panel is so configured that, on a front substrate being one of two substrates are formed a scanning electrode and a common electrode and on a rear substrate being another of the two substrates is formed a data electrode in which writing discharge to select a unit cell to be displayed is performed by driving the data electrode and the scanning electrode while sustaining discharge is performed by surface discharge of the selected unit cell by driving the scanning electrode and the common electrode.
In the three-electrode-surface-discharge type of AC plasma display panel, since ions having high energy being generated at a time of surface discharge on the front substrate move on a plane in a unit cell of the front substrate, a fluorescent material on the rear substrate can avoid interaction with ions and as a result be prevented from deteriorating and, therefore, a lifetime of this type of AC plasma display panel can be made longer and the plasma display is widely used.
FIG. 7 is a cut-away perspective view showing a structure of a conventional three-electrode-surface-discharge type of AC plasma display panel. FIG. 8 is a cross-sectional view of the conventional plasma display panel taken along a line Exe2x80x94E. FIG. 9 is a cross-sectional view of the conventional plasma display panel of FIG. 8 taken along a line Fxe2x80x94F.
In the conventional three-electrode-surface-discharge-type of AC plasma display panel, as shown in FIG. 7 to FIG. 9, on a front substrate 10 constructed of a transparent substrate are formed a plurality of scanning electrodes 5, each of which, is made up of a first transparent electrode 1 and a first metal electrode line 3, and a plurality of common electrodes 6, each of which, is made up of a second transparent electrode 2 and a second metal electrode line 4, in such a manner that a discharge gap 7 may be interposed between each scanning electrode 5 and each common electrode 6 adjacent to each other, and the scanning electrodes 5 and the common electrodes 6 are coated with a dielectric layer 11a and further the dielectric layer 11a is covered with a protective layer 12.
On the other hand, on a rear substrate 13 constructed of a transparent substrate are formed a plurality of data electrodes 14 which are covered with a dielectric layer 11b. Each of belt-shaped partition walls 15 is formed on the dielectric layer 11b and positioned between data electrodes 14 being adjacent to each other.
As shown in FIG. 8, fluorescent materials 16R, 16G, and 16B providing light having three primary colors including light with a red color, light with a green color, and light with a blue color, respectively, are alternately coated (That is to say R, G, B, R, G, B, . . . ) on a surface of the dielectric layer 11b and a side face of each of the belt-shaped partition walls 15. Between the front substrate 10 and the rear substrate 13 are integrally assembled the scanning electrode 5, the common electrode 6, and the data electrode 14 in a manner that they face one another to be orthogonal to one another and in a discharge space 17 being a space between the front substrate 10 and the rear substrate 13 is filled gas emitting ultraviolet rays in an excited state by discharge.
In the conventional plasma display panel described above, three kinds of electrodes including the scanning electrode 5, the common electrode 6, and the data electrode 14 are arranged for every unit cell 9a and one pixel in a screen is made up of three unit cells 9a including the fluorescent materials 16R, 16G, and 16B.
Moreover, among unit cells 9a being adjacent to one another in a column direction V is formed a non-discharge gap 8 to prevent interference against discharge among unit cells 9a. 
Furthermore, since an upper face of each of the belt-shaped partition walls 15 is not covered by the first transparent electrode 1, redundant current being not accompanied by light emission is not consumed. Also, by placing the first transparent electrode 1 in a position being far from an end of each of the belt-shaped partition walls 15, a loss in charged particles is reduced and light emission efficiency is improved.
To drive the conventional plasma display panel described above, control is exerted in such a manner that, by driving the data electrode 14 and scanning electrode 5 using a data pulse and a scanning pulse respectively, writing discharge is performed and that the unit cell 9a to be displayed is selected and by driving the scanning electrode 5 and the common electrode 6, sustaining discharge is performed by surface discharge of the selected unit cell 9a. 
Moreover, to perform sufficient gray-scale, eight to ten sub-fields are provided in one field and each sub-field includes a scanning period to perform writing discharge, a sustaining period to perform sustaining discharge, and a priming period to stabilize writing discharge.
However, the conventional plasma display as shown in FIG. 7 presents a problem in that a width in a row direction H on a screen between the first and second transparent electrodes 1 and 2 facing each other with the discharge gap 7 interposed between them is narrow, causing a discharge voltage to be made high.
Moreover, the conventional plasma display presents another problem in that, if the front substrate 10 and the rear substrate 13 are poorly positioned, the width between the first and second transparent electrodes 1 and 2 is made different depending on a unit cell 9a in a display surface, which causes distribution of discharge voltages to be widened and driving margin to be made narrow.
To solve these problems, an electrode is disclosed in, for example, Japanese Patent Application Laid-open No. Hei 11-297214 in which, as a result of considerations given to a possible influence of a discharge characteristic caused by positioning between a front substrate and a rear substrate, a width of a protruding portion of a transparent electrode has been changed. However, this electrode presents a problem in that, if the protruding portion of the transparent electrode is made slender, a discharge region decreases and, if the protruding portion of the transparent electrode is made thick, excessive charges are readily left on a protective layer in a vicinity of metal electrodes and which causes erroneous discharge.
Moreover, in the conventional plasma display panel shown in FIG. 7, many charges are accumulated in a vicinity of the first and second metal electrode lines 3 and 4 existing at a place being apart from the discharge gap 7 immediately before writing discharge and, by using these charges, the dielectric layer 11a performs writing discharge on the first and second metal electrode lines 3 and 4 being thinner than the first and second transparent electrodes 1 and 2.
To solve this problem, an electrode is disclosed in Japanese Patent Application Laid-open Nos. Hei 10-233171 and Hei 11-297214 in which a dielectric mounted on a metal electrode is formed so as to be thicker than a dielectric mounted on a transparent electrode and not to use discharge occurring on the metal electrode.
Furthermore, another electrode is also disclosed in Japanese Patent Application Laid-open Nos. 2000-106090 and 2000-294149 in which a transparent electrode and a metal electrode is not coupled in a portion facing a discharge space and therefore discharge is not expanded up to regions existing on the metal electrode and, as a result, discharge occurring on the metal electrode is not used.
However, in all the electrodes disclosed above, there are problems in that a writing discharge voltage becomes high, or that a writing operation is erroneously performed, when a charge is accumulated at a place being not far from a discharge gap.
In view of the above, it is an object of the present invention to provide a plasma display panel capable of widening a driving margin and of improving light emission efficiency by lowering a discharge initiating voltage and by increasing erroneous discharge voltage.
According to a first aspect of the present invention, there is provided a plasma display panel including:
a first substrate made up of a transparent material;
a second substrate placed in a manner so as to face the first substrate wherein gas generating ultraviolet rays by discharge excitation is filled in a hermetic manner between the first substrate and the second substrate;
a plurality of transparent electrodes formed on the first substrate, each of which is made up of a first electrode portion, a second electrode portion, and a third electrode portion each being different in a width in a row direction on a screen from;
a plurality of metal electrode lines extending in the row direction and connected to the transparent electrodes;
a plurality of discharge gap formed between the transparent electrodes being adjacent to each other in a column direction;
a plurality of discharge cells made up of a pair of the transparent electrodes out of the plurality of the transparent electrodes, and arranged in a matrix form in a space between the first substrate and the second substrate; and
wherein, in each of the plurality of the discharge cells, the first electrode portion exists in a vicinity of the discharge gap formed on the first substrate or in contact with the discharge gap, both end portions which are respectively positioned on a partition wall between the discharge cells being adjacent to each other in a row direction on a screen, whereby a clearance between end portions of the first electrode portions being adjacent to each other in the row direction is smaller than a width of the partition wall,
the second electrode portion is formed apparent from the metal electrode line, from the discharge gap and from the partition wall, and
the third electrode portion in the row direction on the screen is formed in a vicinity of the metal electrode line or in contact with the metal electrode line, a width of the third electrode portion being smaller than that of the second electrode portion.
In the foregoing, a preferable mode is one wherein a width of each of the first electrode portions in the column direction on the screen is 30 xcexcm to 80 xcexcm.
Another preferable mode is one wherein each of the second electrode portions is formed apart from each of the partition walls by 10 xcexcn to 50 xcexcm.
Still another preferable mode is one wherein a width of each of the first electrode portions in the row direction on the screen is 20 xcexcm to 100 xcexcm.
Furthermore preferable mode is one wherein a width of each of the third electrode portions in the column direction on the screen is 20 xcexcm to 100 xcexcm.
Still furthermore preferable mode is one wherein a clearance between end portions of the first electrode portions being adjacent to each other in the row direction on the screen is 10 xcexcm to 30 xcexcm.
According to a second aspect of the present invention, there is provided a plasma display panel including:
a first substrate made up of a transparent material;
a second substrate being placed in a manner so as to face the first substrate wherein gas generating ultraviolet rays by discharge excitation is filled in a hermetic manner between the first substrate and the second substrate;
a plurality of discharge cells arranged in a matrix form in a space between the first substrate and the second substrate; and
wherein each of the plurality of discharge cells is made up of a scanning electrode and a common electrode facing the scanning electrode through a discharge gap;
wherein the scanning electrode is made up of a first metal electrode line extending in a row direction on a screen and a first transparent electrode being connected to the first metal electrode line;
wherein the common electrode is made up of a second metal electrode line extending in the row direction on the screen and a second transparent electrode being connected to the second metal electrode line;
wherein each of partition walls extending in a column direction on the screen is formed between the scanning electrodes being adjacent to each other and between the common electrodes being adjacent to each other on the second substrate:
wherein each of the first transparent electrode and the second transparent electrode is made up of a first electrode portion, a second electrode portion and a third electrode portion each having a different width in the row direction on the screen and being formed integrally in the column direction on the screen;
wherein the first electrode portion exists in a vicinity of the discharge gap formed on the first substrate or in contact with the discharge gap, both end portions which are respectively positioned on a partition wall between the discharge cells being adjacent to each other in a row direction on a screen, whereby a clearance between end portions of the first electrode portions being adjacent to each other in the row direction is smaller than a width of the partition wall,
wherein the second electrode portion is formed apparent from the metal electrode line, from the discharge gap and from the partition wall, and
wherein the third electrode portion in the row direction on the screen is formed in a vicinity of the metal electrode line or in contact with the metal electrode line, a width of the third electrode portion being smaller than that of the second electrode portion.
According to a third aspect of the present invention, there is provided a plasma display panel including:
a first substrate made up of a transparent material;
a second substrate placed in a manner so as to face the first substrate wherein gas generating ultraviolet rays by discharge excitation is filled in a hermetic manner between the first substrate and the second substrate;
a plurality of transparent electrodes formed on the first substrate, each of which is made up of a first electrode portion, a second electrode portion, and a third electrode portion each being different in a width in a row direction on a screen from;
a plurality of metal electrode lines extending in the row direction and connected to the transparent electrodes;
a plurality of discharge gap formed between the transparent electrodes being adjacent to each other in a column direction;
a plurality of discharge cells made up of a pair of the transparent electrodes out of the plurality of the transparent electrodes, and arranged in a matrix form in a space between the first substrate and the second substrate; and
wherein, in each of the plurality of the discharge cells, the first electrode portion is connected to another first electrode portion in the adjacent discharge cell in the row direction on the screen,
the second electrode portion is formed apparent from the metal electrode line, from the discharge gap and from the partition wall, and
the third electrode portion in the row direction on the screen is formed in a vicinity of the metal electrode line or in contact with the metal electrode line, a width of the third electrode portion being smaller than that of the second electrode portion.
According to a fourth aspect of the present invention, there is provided a plasma display panel including:
a first substrate made up of a transparent material;
a second substrate being placed in a manner so as to face the first substrate wherein gas generating ultraviolet rays by discharge excitation is filled in a hermetic manner between the first substrate and the second substrate;
a plurality of discharge cells arranged in a matrix form in a space between the first substrate and the second substrate; and
wherein each of the discharge cells is made up of a scanning electrode and a common electrode facing the scanning electrode through a discharge gap;
wherein the scanning electrode is made up of a first metal electrode line extending in a row direction on a screen and a first transparent electrode being connected to the first metal electrode line;
wherein the common electrode is made up of a second metal electrode line extending in the row direction on the screen and a second transparent electrode being connected to the second metal electrode line;
wherein each of partition walls extending in a column direction on the screen is formed between the scanning electrodes being adjacent to each other and between the common electrodes being adjacent to each other on the second substrate;
wherein each of the first transparent electrode and the second transparent electrode is made up of a first electrode portion, a second electrode portion and a third electrode portion each having a different width in the row direction on the screen and being formed integrally in the column direction on the screen;
wherein, in each of the plurality of the discharge cells, the first electrode portion is connected to another first electrode portion in the adjacent discharge cell in the row direction on the screen,
wherein the second electrode portion is formed apparent from the metal electrode line, from the discharge gap and from the partition wall, and
wherein the third electrode portion in the row direction on the screen is formed in a vicinity of the metal electrode line or in contact with the metal electrode line, a width of the third electrode portion being smaller than that of the second electrode portion.
With the above configuration, since a width of each of the first electrode portions facing each other with the discharge gap being interposed between the first electrode portions can surely be large, even if a deviation in assembling between the front substrate and the rear substrate or a difference in contraction of the substrate caused by baking occurs, a discharge initiating voltage can be lowered.
With another configuration, since mounting of the transparent electrode portions not affecting much the discharge initiating voltage, for example, of the transparent electrode portions being placed on each of the partition walls is omitted; that is, since the second electrode portions and the third electrode portions are positioned apart from each of the partition walls so as not to cover each of the partition walls and, in order to ensure absolute luminance, the width of each of the second electrode portions in the row direction on the screen is set not to be excessively small, it is possible to avoid a flow of an excessive current and efficiency of light emission can be improved Moreover, since the width of the third electrode portions in the row direction on the screen is made smaller within a range in which writing discharge is not made high, an erroneous discharge voltage can be made higher. Therefore, since the discharge initiating voltage is low and the erroneous discharge voltage is high, a driving margin is made wider and stable operation can be achieved. Furthermore, since the first electrode portions are connected to each other in each of the discharge cells in the row direction on the screen, even if a breakage occurs in the third electrodes, since a current can be fed through the first electrode portions from discharge cells and therefore it is possible to operate each discharge cell in a stable manner.